Posttraumatic stress disorder (PTSD) affects 7-9% of American adults over their lifetime and is estimated to cost the US over $23 billion per year. Prolonged Exposure (PE) is one of the most effective treatments for PTSD, but under-engagement, poor adherence, and dropout limit recovery for many patients. Improved tracking and feedback of engagement level, homework adherence, and measures indicating dropout risk would help therapists modify treatment, reinforce progress, and motivate patients to continue therapy. Unfortunately, current methods of clinical evaluation (i.e. structured interviews and questionnaires) are insufficient as they are subjective, relatively infrequent (e.g. weekly), and dependent on the patient's self-report accuracy and motivation. The addition of objective physiologic data could yield a more comprehensive assessment of engagement and treatment response. While physiologic monitoring devices exist, they are too complex and cumbersome, lack the needed parameters and sensitivity, and have not been developed for use with PE. A PTSD-specific solution is needed that can integrate relevant physiologic and psychometric data to better assess treatment effects and improve patient acceptance, engagement, and adherence. To solve this problem, Aclaris Medical, LLC (Aclaris), is teaming with the Center for the Treatment and Study of Anxiety (CTSA) and a world-class group of clinical, scientific, and human factors usability advisors to demonstrate the feasibility of a novel monitoring system to advance PE for PTSD patients. When developed, this product will utilize physiologic data collected by Aclaris's Autonomic Wrist Monitor (AWM), psychometric data collected by the company's Therapist App, and ecological momentary assessment (EMA) data collected by the company's Patient App. The collected data will be integrated for display in the Therapist App to help the therapist assess engagement, homework adherence, and dropout risk so they can intervene before it is too late. Preliminary data from Aclaris sets the stage for successfully meeting the Phase I aims to demonstrate feasibility: Aim 1- Prove Feasibility of Therapist App and Patient App. Aim 2-Prove Feasibility of AWM during PE. Aim 3-Prove Feasibility of PTSD Monitoring System. At the end of Phase I, the company expects to achieve a functional prototype of the PTSD Monitoring System, an assessment of its feasibility, and insight on how to best deploy it for use with PE. In Phase II, Aclaris will further develop the monitoring system and conduct a larger study with PTSD patients at CTSA comparing conventional PE to PE enhanced with the PTSD Monitoring System. Phase II success will provide the data needed to approach the Department of Veterans Affairs and Department of Defense for a larger multi-center pilot evaluation and attract additional private investment for FDA approval and civilian commercialization. Beyond PTSD, the company plans to expand the use of the platform to research and treat other mental health disorders and conditions (e.g. phobias, panic disorder, social anxiety disorder, and common stress) as well as chronic medical conditions affecting the autonomic nervous system.